1. Field of the Invention
This invention relates to a paging receiver, and more particularly to a paging receiver for use with a plurality of paging systems having different radio frequencies.
2. Description of the Prior Art
In a paging receiver for use with a plurality of paging service systems which use different radio frequency channels, the receiver must search a radio frequency band in which the radio frequency channels are included and receive the radio frequency channels selectively in order to distinguish for each of channels successively received whether or not the paging receiver itself is entitled to use the channel. To this end, each radio frequency channel includes system information for identification of the paging system, and the receiver compares the system information included in channels successively received with the system information held by the receiver itself. Then, when the system information coincides with the information held by the receiver, the receiver fixes the local frequency in order to continue the reception of the channel as an object channel and to identify subsequent paging information, but when the information does not coincide, the receiver changes the local frequency in order to change the reception channel to the next order radio frequency channel.
In this instance, conventional searching operations of the receiver are performed similarly for channels not being transmitted (not operated) and for channels whose received electric field strength is so low that the signals cannot be received correctly, and since a time of several hundred milliseconds is required to receive a minimum unit of transmission signals for every reception channel, the time required to search for, for example, 16 radio frequency channels is as long as several seconds.
Consequently, a long time is required before the receiver enters a battery saving condition, resulting in degradation of the life of the battery. Further, there is another drawback in that, as the time for searching for all radio frequency channels increases, the probability increases that the paging receiver will fail to receive a paging call sent to the paging receiver.